2,3,6-substituted phenylimidazole derivatives and the use thereof as growth regulators

ABSTRACT

The compounds of the formula I, or salts thereof, ##STR1## in which R 1  and R 2 , independently of one another, denote (C 1  -C 4 )-alkyl, 
     R 3  denotes halogen, in particular Cl or Br, 
     R 4  denotes hydrogen, Cl, Br or methyl, 
     X denotes O, S or N-R 5 , and 
     R 5  denotes hydrogen, (C 2  -C 6 )-alkenyl or (C 1  -C 6 )-alkyl, where the alkyl group may be up to disubstituted by (C 1  -C 6 )-alkoxy or (C 1  -C 3 )-dialkylamino, or up to hexasubstituted by halogen, 
     have an excellent plant growth-regulating action in important crops.

DE-A No. 3,217,094 discloses 1-phenylimidazole-5-carboxylic acidderivatives and the use thereof as fungicides, herbicides and plantgrowth regulators.

Surprisingly, it has now been found that selected imidazole compoundswhich are substituted by halogen in the 3-position of the phenyl ringhave a particularly intensive growth-regulating action.

The present invention therefore relates to compounds of the formula I##STR2## in which R¹ and R², independently of one another, denote (C₁-C₄)-alkyl,

R³ denotes halogen, in particular Cl or Br,

R⁴ denotes hydrogen, Cl, Br or methyl,

X denotes O, S or N-R⁵, and

R⁵ denotes hydrogen, (C₂ -C₆)-alkenyl or (C₁ -C₆)-alkyl, where the alkylgroup may be up to disubstituted by (C₁ -C₆)-alkoxy or (C₁-C₃)-dialkylamino, or up to hexasubstituted by halogen,

and the salts and quaternization products thereof which are acceptablefor agricultural purposes.

Possible halogenated (C₁ -C₆)alkyl for R⁵ are, in particular, thehexafluoropropyl, 2,2,3,3-tetrafluoropropyl, 2,2,2-trifluoroethyl,2,2,2-trichloroethyl and 2,2,3,4,4,4-hexafluorobutyl radicals.

Salt formation or quaternization occurs either at the --COOH or (C═O)-SHgroup (X=O or S; R⁵ =H) or at the basic nitrogen atom of the imidazolering. Salt formation or quaternization at the imidazole ring is notpossible when R⁵ contains a cation. Halogen is taken to mean F, Cl, Bror I, in particular F, Cl or Br.

All inorganic or organic acids which are capable, as a consequence oftheir pKs value, of forming salts, for example hydrohalic acids, nitricacid, sulfuric acid, phosphoric aicd, phosphonic acids, sulfonic aicds,haloacetic acids or oxalic acid, are suitable for the salts.

Possible cations which can be employed in agriculture are metal cations,for example alkali metal or alkaline earth metal cations, such as Na, Kor Mg, or ammonium, or organic cations, such as, for example, ammonium,phosphonium, sulfonium or sulfoxonium ions which are substituted byorganic radicals, or optionally substituted hydrazonium,hydroxylammonium, guanidinium or aminoguanidinium.

Organically substituted ammonium denotes primary, secondary, tertiary orquaternary, aliphatic, aromatic or heteroaromatic ammonium which maycontain 1 to three nitrogen atoms. The nitrogen atoms of the amine canin this case also be part of a cyclic system. Examples of such ammoniumsalts which may be mentioned are: mono-, di-, tri- and tetra[(C₁-C₆)alkyl]ammonium, such as isopropylammonium, butylammonium,stearylammonium, triethylammonium, mono-, di- and tri-[(C₁ -C₄)alkoxy(C₁-C₄)alkyl]ammonium or mono-, di- and tri-[(C₁ -C₆)alkanol]ammonium, suchas methoxyethylammonium, methoxypropylammonium, triethanolammonium ortripropanolammonium, or ammonium compounds containing mixed radicals,such as tert.-butyldiethanolammonium, triethylenebenzylammonium,hydroxyethyltrimethylammonium or chloroethyltrimethylammonium; orallylammonium, diallylammonium, cyclohexylammonium, menthylammonium,aminoethylammonium, ethylenediammonium, benzohydrylammonium,pyrrolidinium, morpholinium, 3-pyridylammonium, piperidinium orpiperazinium, or ammonium which is derived from an amino acid or anester thereof, such as .sup.⊕ NH₃ --CH₂ --COOCH₃.

Corresponding radicals as in the case of ammonium can be present in theother abovementioned organic cations.

The invention furthermore relates to processes for the preparation ofcompounds of the formula I and the salts or quaternization productsthereof, wherein

(a) a tantomeric bisformyl ester of the formula (IIa) or (IIb) ##STR3##

in which R⁶ denotes (C₁ -C₁₂)-alkyl, is heated in the presence ofammonia or a compound which liberates ammonia, or

(b) an aminophenyl derivative of the formula III ##STR4## is diazotizedand subsequently reacted with a halide in accordance with the Sandmeyerreaction, or

(c) in the case where R³ represents chlorine or bromine, aphenylimidazole derivative of the formula IV ##STR5## is brominated orchlorinated, or the compounds obtained under (a), (b) or (c) arederivatized.

In the derivatization, the --COOR⁶ radical is modified in a knownfashion, for example by saponification, esterification,transesterification, amidation or salt formation, as described, forexample, in Patent Applications DE-A Nos. 3,444,918 and 3,442,690, orsalt formation or quaternization takes place at the basic nitrogen atomof the imidazole ring.

Concerning

(a) The formyl compounds IIa/IIb can be prepared from the correspondinganilines by known processes, as described, for example, in DE-A No.3,217,094. The formyl compounds are cyclized in the presence of ammoniaor substances which form ammonia when heated, such as, for example,ammonium acetate, ammoniumbenzoate or formamide, or in the presence ofhighboiling solvents, such as, for example, xylene or formamide, attemperatures from 100° to 200° C.

Concerning

(b) The amino compounds are accessible from the known imidazoles of theformula IV (DE-A No. 3,217,094) by nitration and reduction. TheSandmeyer reaction can be carried out in good yields under conventionalreaction conditions (cf., for example, Organikum, VEB Deutscher Verlagder Wissenschaften Berlin 1973, pp. 590 ff).

Concerning

(c) The halogenation can likewise be carried out from the knowncompounds of the formula IV by conventional processes (cf., for example,Organikum, see above, pp. 342 ff).

The salts of the compounds of the formula (I) can be obtained in asimple fashion by conventional salt-formation methods, for example bydissolving a compound of the formula (I) in a suitable organic solventand adding the acid, and can be purified in a known fashion, for exampleby filtering off, isolating and optionally washing with an inert organicsolvent.

The compounds according to the invention can achieve typicalgrowth-regulating effects which--compared to the compounds known fromDE-A No. 3,217,094--can surprisingly be achieved even at very lowdosages.

The compounds according to the invention engage in a regulating mannerin the plant's own metabolism and can therefore be employed to influenceplant constituents in a specific manner and to simplify harvesting, suchas for initiating desiccation and growth inhibition. In addition, theyare suitable for general control and inhibition of undesired vegetativegrowth, without at the same time destroying the plants. Inhibition ofvegetative growth plays a major part in many mono- and dicotyledon cropssince lodging can thereby be reduced or completely prevented. Thegrowth-regulating activity of the compounds as growth inhibitors incereals, corn, soybean, tobacco, cotton, horse beans, rape, rice,sunflowers and turf, and their ability to increase the content ofdesired constituents such as carbohydrates (for example sugar cane ormillet crops) and protein in crop plants should be particularlyemphasized.

When used in practice, the compounds according to the invention canalso, if appropriate, be advantageously combined with known growthregulators. Such known growth regulators are the compounds of theformula (V)

    R--CH.sub.2 --CH.sub.2 --N.sup.+ (CH.sub.3).sub.3 Cl.sup.- (V)

in which R denotes OH or Cl (common name chlormequat for R=Cl),furthermore, N,N-dimethylpiperidinium chloride (VI; common name:mepiquat chloride), α-cyclopropyl-4-methoxy-α-(pyrimidin-5-y)benzylalcohol (VIII; common name: ancymidol), (3aα, 4β, 4aα, 6aα, 7β,7aα)-1-(4-chlorophenyl)-3a, 4, 4a, 6a, 7,7a-hexahydro-4,7-methano1H-[1,2]diazeto[3,4-f]benzotriazole (VIII;common name: tetcylacis), 2,2-dimethylsuccinomonohydrazide (IX, commonname: diaminoazide), 6-hydroxy-2H-pyridazin-3-one (X, maleic anhydride),2-chloro-9-hydroxy-9H-fluorene-9-carboxylic acid (XI, chlorflurenol),N-[2,4-dimethyl-5-[[(trifluoromethyl)sulfonyl]amino]phenyl]acetamide(mefluidide) and 2-chloroethylphosphonic acid (XIII, ethephon).

The growth-regulating actions of the compounds of the formulae (V) to(XIII) are described in Plant Growth Regulator Handbook of the PlantGrowth Regulator Working Group, 2nd Ed., 1981.

In place of the compounds of the formulae (V) and (VI), comparable saltswhich contain another conventional anion, such as bromide, nitrate or1/2 sulfate, in place of the chloride ion, can be employed in principle.

Combinations can exist both as mixed formulations of the components,which are then used diluted with water in a conventional fashion; orthey can be prepared as so-called tank mixes by common dilution withwater of the separately formulated components; it is also possible touse the components in succession, i.e. the components are then appliedin individual formulations.

The compounds of the general formula (I) may also be combined withnatural or vegetative hormones, such as auxins or cytokinins.

A further solution of the object set are also plant growth-regulatingagents which are distinguished by an active content of at least one ofthe compounds according to the invention.

The compounds according to the invention can be applied in conventionalpreparations, if appropriate mixed with further active components, suchas wettable powders, emulsifiable concentrates, sprayable solutions,dusts, dispersions, granules or microgranules.

Wettable powders are preparations which are uniformly dispersible inwater and which contain, besides the active compound(s) and in additionto any diluent or inert material, wetting agents, such aspolyoxyethylated fatty alcohols, alkylsulfonates oralkylphenylsulfonates, and/or dispersants, such as sodiumlignin-sulfonate, sodium 2,2'-dinaphthylmethane-6,6'-disulfonate, sodiumdibutylnaphthalenesulfonate or sodium oleoylmethyltaurinate. Thepreparation is carried out in the conventional fashion, for example bygrinding and mixing the components.

Emulsifiable concentrates can be prepared, for example, by dissolvingthe active ingredients in an inert, organic solvent, such as butanol,cyclohexanone, dimethylformamide, xylene or higher-boiling aromatics oraliphatic or cycloaliphatic hydrocarbons, with addition of one or moreemulsifiers. In the case of liquid active ingredients, the solventcomponent can also be omitted entirely or partly. As emulsifiers, thefollowing can be used, for example: calcium salts ofalkylarylsulfonates, such as Ca dodecylbenzenesulfonate, or nonionicemulsifiers, such as fatty acid polyglycol esters, alkylaryl polyglycolesters, fatty alcohol polyglycol ethers, propylene oxide/ethylene oxidecondensation products, fatty alcohol/propylene oxide condensationproducts, alkyl polyglycol ethers, sorbitan fatty acid esters,polyoxyethylene sorbitan fatty acid esters or polyoxyethylene sorbitolesters.

Dusts can be obtained by grinding the active ingredients with finelydivided solid substances, for example talcum, natural clays, such askaolin, bentonite or pyrophillite, or diatomaceous earth. Granules canbe prepared either by atomizing the active ingredients onto adsorptive,granulated inert material or by applying active ingredient concentratesonto the surface of carrier materials, such as sand or kaolinites, or ofgranulated inert material by means of binders, for example polyvinylalcohol or sodium polyacrylate, or alternatively mineral oils. Suitableactive ingredients can also be granulated--if desired as a mixture withfertilizers--in the fashion which is conventional for the preparation offertilizer granules.

In wettable powders, the active compound concentration is about 5 to 90%by weight, and the remainder to 100% by weight comprises conventionalformulation components. In the case of emulsifiable concentrates, theactive ingredient concentration can be about 3 to 80% by weight.Dust-form formulations usually contain 0.025 to 20% by weight of activeingredient(s), and sprayable solutions about 2 to 20% by weight. In thecase of granules, the active ingredient content depends partly onwhether the active compound is liquid or solid and which granulationauxiliaries, fillers etc. are used. In addition, the active ingredientformulations mentioned contain, if appropriate, the adhesives, wettingagents, dispersants, emulsifiers, penetrants, solvents, fillers orexcipients which are conventional in each case.

For use, the concentrates, present in commercially available form, arediluted, if appropriate, in a conventional fashion, for example usingwater in the case of wettable powders, emulsifiable concentrates,dispersions and, in some cases, also in the case of microgranules.Dust-form and granulated preparations and sprayable solutions are notusually diluted with further inert substances before application.

The application rate of the compounds according to the inventiongenerally varies between 0.02 and 2.5 kg of active substance perhectare, preferably 0.05 to 1.5 kg/ha.

The examples below are intended to illustrate the invention.

FORMULATION EXAMPLES Example 1

A dusting agent is obtained by mixing (a) 10 PW.sup.(1) of activeingredient with 90 PW of talcum or another inert substance andcomminuting in a hammer mill, or by (b) homogenizing 60 PW of activeingredient, 35 PW of talcum and 5 PW of adhesive (for example apolysaccharide such as ®Rhodopol supplied by Rhone-Poulenc S.A.) in thesame fashion.

Example 2

A wettable powder which is easily dispersible in water is obtained bymixing 25 PW of active ingredient, 64 PW of kaolin-containing quartz asinert material, 10 PW of potassium ligninsulfonate and 1 PW of sodiumoleoylmethyltaurinate as wetting agent and dispersant, and grinding in apin disk mill. A formulation containing 5% of active ingredient can becomposed as follows: 5% of active ingredient, 6% of a sulfonatednaphthalene-formaldehyde condensate (for example ®Dispersogen A suppliedby Hoechst AG), 2% of an Na salt of an alkylnaphthalenesulfonic acid(for example ®Leonil DB supplied by Hoechst AG), 5% of a mixture ofpolypropylene glycol and SiO₂ (for example ®Acrotin 341 supplied byHoechst AG), 25% of a silicate (for example ®Sipernat supplied byDegussa AG) and 57% of kaolin type 1777.

Example 3

A dispersion concentrate which is easily dispersible in water isobtained by mixing 20 PW of active ingredient with 6 PW of analkylphenol polyglycol ether (for example ®Triton X 207 supplied by Rohmand Haas Co.), 3 PW of isotridecanol polyglycol ether (8 ethylene oxideunits) and 71 PW of paraffinic mineral oil (boiling range about 255 toabove 377° C.), and grinding in a ball mill to a fineness of below 5 μm.

Example 4

An emulsifiable concentrate is obtained from 15 PW of activeingredient(s), 75 PW of cyclohexanone as solvent and 10 PW ofoxyethylated nonylphenol (10 ethylene oxide units) as emulsifiers.

CHEMICAL EXAMPLES Example 1 Ethyl1-(3-chloro-6-ethyl-2-methylphenyl)-imidazole-5-carboxylate

19.2 g (0.068 mol) of ethyl2-(3-chloro-6-ethyl-2-methyl-N-formylanilino)-3-hydroxy-acrylate wereheated to an internal temperature of 153° C. with 12.3 g (0.088 mol) ofammonium benzoate in 100 ml of xylene with removal of the xylene/watermixture by distillation. The mixture was allowed to cool and was takenup in toluene, and the organic phase was washed twice with 2N sodiumhydroxide solution and twice with water, dried over sodium sulfate andevaporated. 15.2 g (85% of theory) of ethyl1-(3-chloro-6-ethyl-2-methylphenyl)-imidazole-5-carboxylate wereobtained as a pale brown oil. Identification was effected by ¹ H NMRspectroscopy.

Example 2 Ethyl 1-(3-bromo-2,6-diethylphenyl)-imidazole-5-carboxylate

20 g (0.07 mol) of ethyl1-(3-amino-2,6-diethylphenyl)imidazole-5-carboxylate were added to amixture of 30 ml of concentrated hydrobromic acid, 30 ml of glacialacetic acid and 30 ml of water, the mixture was cooled to 0° C., and asolution of 12.0 g (0.17 mol) of sodium nitrite in 15 ml of water wasadded dropwise at this temperature. After 30 minutes at 0° C., theexcess nitrite was decomposed using urea, and the solution was addeddropwise at 0° C. to a copper bromide solution (prepared by conventionalprocesses from 24.9 g of copper sulfate, 15.5 g of sodium bromide, 6.3 gof sodium sulfite, 80 ml of water and 40 ml of concentrated hydrobromicacid). The reaction mixture was allowed to warm to room temperature andwas neutralized, the product was extracted with methylene chloride, andthe organic phase was washed with water, dried over sodium sulfate andevaporated. After chromatographic purification, 17.4 g (71% of theory)of ethyl 1-(3-bromo-2,6-diethylphenyl)-imidazole-5-carboxylate wereobtained as a pale yellow oil. Identification was effected by ¹ H NMRspectroscopy.

Example 3 1-(3-Bromo-2,6-diethylphenyl)-imidazole-5-carboxylic acid

17.4 g of the ethyl ester described in Example 2 were heated for 1 hourat 80° C. with 150 ml of 2N sodium hydroxide solution. After cooling,the mixture was acidified to pH 3 using concentrated hydrochloric acid,and the colorless solid was filtered off under suction. After drying,11.6 g (72% of theory) of1-(3-bromo-2,6-diethylphenyl)-imidazole-5-carboxylic acid of meltingpoint 224°-7° C. were obtained.

The following examples can be prepared by the process described above.

When Y represents radicals other than --COOCH₃ and --COOC₂ H₅ in Table1, these were prepared from the appropriate esters by conventional,generally known processes, such as, for example, saponification (Example3), subsequent preparation of the acyl chloride and reaction withalcohols, amines or thiols; or reaction of the acid with bases for saltformation.

                                      TABLE 1                                     __________________________________________________________________________    Imidazole derivatives                                                          ##STR6##                                                                     Example No.                                                                          R.sup.1                                                                             R.sup.2                                                                             R.sup.3                                                                         R.sup.4                                                                           Y                   m.p./b.p. (°C.)           __________________________________________________________________________    4      CH.sub.3                                                                            CH.sub.3                                                                            Br                                                                              H   COOCH.sub.3         132-5                            5      "     "     " "   COOH                227-9                            6      "     "     " "   COO.sup.⊖.NH.sub.4.sup.⊕                 7      "     "     " "   C(O)SC.sub.2 H.sub.5                                 8      "     "     " "   C(O)SCH.sub.3                                        9      "     C.sub.2 H.sub.5                                                                     Cl                                                                              "   COOH                179-82                           10     "     "     " "   COOK                                                 11     "     "     " "   COO.1/2Mg                                            12     "     "     " "   COOCH.sub.3         101                              13     "     "     " "   COOC.sub.2 H.sub.5  135-7/0.01 torr                  14     "     "     " "   C(O)NH.sub.2        168-72                           15     "     "     " "   C(O)i-NH C.sub.4 H.sub.9                             16     "     "     " "   C(O)NHCH.sub.3      209-13                           17     "     "     " "   C(O)N(CH.sub.3).sub.2                                                                             oil                              18     "     "     " "   C(O)NH(CH.sub.2).sub.3OCH.sub.3                      19     "     "     " "   C(O)N(CH.sub.3)CH(CH.sub.3).sub.2                    20     "     "     " "   COOCH.sub.2CCl.sub.3                                 21     "     "     " "   C(O)NHCH.sub.2CHCH.sub.2                             22     "     "     " "   COOCH.sub.3 (Hydrochloride)                          23     C.sub.2 H.sub.5                                                                     CH.sub.3                                                                            " "   COOH                185-92                           24     "     "     " "   COO.sup.-.[N(C.sub. 2 H.sub.5).sub.4 ].sup.+         25     "     "     " "                                                                                  ##STR7##                                            26     "     "     " "   COONa                                                27     "     "     " "   COO.sup.⊖.S.sup.⊕ (CH.sub.3).sub.3       28     "     "     " "   COOCH.sub.3         105-10                           29     "     "     " "   COOi-C.sub.3 H.sub.7                                                                              oil                              30     "     "     " "   COOC.sub.6 H.sub.13                                  31     "     "     " "   COO(CH.sub.2).sub.2OC.sub.2 H.sub.5                  32     "     "     " "   COOCH(CF.sub.3).sub.2                                33     "     "     " "   C(O)NH.sub.2        170                              34     "     "     " "   C(O)N(C.sub.2 H.sub.5).sub.2                                                                      oil                              35     "     "     " "   C(O)N(CH.sub.3)CH(CH.sub.3).sub.2                    36     "     "     " "   C(O)N(CH.sub.2CHCH.sub.2).sub.2                      37     "     C.sub.2 H.sub.5                                                                     " "   COOH                210-4 (decomp.)                  38     "     "     " "   COONa               144-8                            39     "     "     " "   COOK                210-14                           40     "     "     " "   COO.sup.⊖ [HN(CH.sub.2CH.sub.2OH).sub.3                               ].sup.⊕          89-94                           41     "     "     " "   COO.sup.⊖ [P.sup.⊕ (CH.sub.3)(Phenyl)                             .sub.3 ]                                             42     "     "     " "   COOH (Hydrochloride)                                 43     "     "     " "   COOH(2-Chlorethyl-                                                            phosphonate                                          44     "     "     " "   COOH (Sulfonate)                                     45     "     "     " "   COOCH.sub.3                                          46     "     "     " "   COOC.sub.2 H.sub.5  153-7/0.01 torr                  47     "     "     " "   COOCH.sub.2CF.sub.3                                  48     "     "     " "   COOCH.sub.2CHFCF.sub.2CF.sub.3                       49     "     "     " "   COOCH.sub.2CH.sub.2N(C.sub.2 H.sub.5).sub.2          50     "     "     " "   COOn-C.sub.3 H.sub.7                                                                              oil                              51     "     "     " "   COOCH.sub.2CHCH.sub.2                                                                             oil                              52     "     "     " "   COOn-C.sub.6 H.sub.13                                53     "     "     " "   COOi-C.sub.3 H.sub.7                                 54     "     "     " "   C(O)NH.sub.2        188-93                           55     "     "     " "   C(O)NHCH.sub.2CH(OCH.sub.3).sub.2                                                                 110-4                            56     "     "     " "   C(O)N(CH.sub.3)[CH.sub.2CH(OC.sub.2 H.sub.5).sub.                             2 ]                                                  57     "     "     " "   C(O)NHi-C.sub.3 H.sub.5                              58     "     "     " "   C(O)NHCH.sub.2i-C.sub.3 H.sub.7                      59     "     "     " "   C(O)NHCH.sub.3      187-94                           60     "     "     " "   C(O)N(CH.sub.3).sub.2                                                                             oil                              61     "     "     " "   C(O)SH                                               62     "     "     " "   C(O)SC.sub.2 H.sub.5                                 63     "     "     " 4-Br                                                                              COOH                                                 64     "     "     " "   COOC.sub.2 H.sub.5  70-6                             65     "     "     " "   COOCH.sub.3                                          66     "     "     " "   COO 1/2Ca                                            67     "     "     " 4-Br                                                                              .C(O)NH.sub.2                                        68     "     "     " "   C(O)NHn-C.sub.6 H.sub.13                             69     "     "     " 4-CH.sub.3                                                                        COOH                213-5                            70     "     "     " "                                                                                  ##STR8##           resin                            71     "     "     " "   COOCH.sub.3         oil                              72     "     "     " "   COOC.sub.2 H.sub.5  oil                              73     "     "     " "   COO(CH.sub.2).sub.2OCH.sub.3                         74     "     "     " "   C(O)NH.sub.2        163-5                            75     "     "     " "   C(O)NH.sub.2 (Hydrochloride)                         76     "     "     " "   C(O)NHC.sub.4 H.sub.9                                77     "     "     " 5-Cl                                                                              COOH                 197-202                         78     "     "     " "   COO.sup.⊖ [HN.sup.(+) (C.sub.2 H.sub.5).s                             ub.2 ]                                               79     "     "     " "   COO.sup.⊖ [ClCH.sub.2CH.sub.2N.sup.⊕                              (CH.sub.3).sub.3 ]                                   80     "     "     " "   COOCH.sub.3         32-4                             81     "     "     " "   COOC.sub.2 H.sub.5  132-36                           82     "     "     " "   COOCH(CH.sub.3)C.sub.6 H.sub.13                      83     "     "     " "   C(O)NH.sub. 2       179-85                           84     "     "     " "   C(O)NHCH(CH.sub.3).sub.2                             85     "     "     " "   C(O)NHi-C.sub.5 H.sub.11                             86     "     "     " "   C(O)N(CH.sub.3)CH.sub.2 CF.sub.3                     87     "     "     F H   COOH                                                 88     "     "     " "   COOCH.sub.3                                          89     "     "     " "   COOC.sub.2 H.sub.5                                   90     "     "     " "   C(O)NH.sub.2                                         91     "     "     I "   COOH                202-4                            92     "     "     " "   COOC.sub.2 H.sub.5  oil                              93     "     "     Cl                                                                              "   COOH                                                 94     "     "     " "   COOC.sub.2 H.sub.5                                   95     "     "     " "   C(O)NH.sub.2                                         96     "     "     " 5-CH.sub.3                                                                        COOH                                                 97     "     "     " "   COOC.sub.2 H.sub.5                                   98     "     "     " "   C O)NH.sub.2                                         99     "     "     " "   C O)NHCH.sub.3                                       100    CH(CH.sub.3).sub.2                                                                  CH(CH.sub.3).sub.2                                                                  " H   COOH                                                 101    "     "     " "                                                                                  ##STR9##                                            102    "     "     " "   COO.sup.(-)./2Zn.sup.(+)                             103    "     "     " "   COOCH.sub.3                                          104    "     "     " "   COO(CH.sub.2).sub.2OC.sub.4 H.sub.9                  105    "     "     " "   COOCH(CF.sub.3).sub.2                                106    "     "     " "   C(O)NH.sub.2                                         107    "     "     " "   C(O)N(CH.sub.3).sub.2                                108    "     "     " "   C(O)NHCH.sub.2CHCH.sub.2                             109    "     "     " "   C(O)NHC.sub.6 H.sub.13                               110    "     "     " "   C(O)NH(CH.sub.2).sub.3 N(C.sub.2 H.sub.5).sub.2      111    CH.sub.3                                                                            CH.sub.3                                                                            Br                                                                              "   COOC.sub.2 H.sub.5   78-81                           112    "     "     " "   COOC.sub.3 H.sub.7  100-5                            113    "     "     " "   COOCH(CF.sub.3).sub.2                                                                             92-5                             114    "     "     " "   CONHCH.sub.3        202-6                            115    "     "     " "   CON(CH.sub.3).sub.2 oil                              116    "     "     " "   CONHCH(CH.sub.3).sub.2                                                                            90-5                             117    "     C.sub.2 H.sub.5                                                                     Cl                                                                              "   COOCH(CH.sub.3).sub.2                                                                              59-63                           118    "     "     " "   COOCH(CF.sub.3).sub.2                                                                             oil                              119    "     "     " "   COOCH.sub.2CHCH.sub.2                                                                             oil                              120    "     "     " "   CONHC.sub.2 H.sub.5 oil                              121    "     C.sub.2 H.sub.4                                                                     " "   CONHCH(CH.sub.3).sub.2                                                                            171                              122    "     "     " "   CONHCH.sub.2 C(CH.sub.3).sub.3                                                                    165-9                            123    C.sub.2 H.sub.5                                                                     "     " "   COOLi               278-83                           124    "     "     " "   COOCH(CF.sub.3).sub.2                                                                             oil                              125    "     "     " "   COOCH.sub.2 CF.sub.2 CHFCF.sub.3                                                                  oil                              126    "     "     " "   CON(CH.sub.3)CH.sub.2 CH(OCH.sub.3).sub.2                                                         oil                              127    "     "     " "   CONHCH.sub.2 CH(OC.sub.2 H.sub.5).sub.2                                                           158-60                           128    "     "     " "   CONHC.sub.3 H.sub.7 176-80                           129    "     "     " "   CON(CH(CH.sub.3).sub.2).sub.2                                                                     oil                              130    "     "     " "   CONHCH.sub.2 OC.sub.2 H.sub.5                                                                      85-88                           131    "     "     " "   CONHCH.sub.2 OCH.sub.3                               132    "     "     " "   CONHCH.sub.2 OC.sub.3 H.sub.7                        133    "     "     Br                                                                              "   COOK                >250                             134    "     "     " "   CONH.sub.2          211-3                            135    "     "     " "   CONHCH.sub.2 CH(OCH.sub.3).sub.2                                                                   98-101                          136    "     "     Cl                                                                              5-Cl                                                                              COOK                >270                             137    "     "     " "   COOCH(CH.sub.3).sub.2                                                                             80-4                             138    "     "     " "   COOC.sub.3 H.sub.7  oil                              139    "     "     " "   COSC.sub.4 H.sub.9  oil                              140    "     "     " "   CONHCH.sub.3        190-5                            141    "     "     " "   CON(C.sub.2 H.sub.5).sub.2                                                                        92-7                             142    "     "     " 4-CH.sub.3                                                                        COONa               >300                             143    "     "     " "   COOK                214-6                            144    "     "     " "                                                                                  ##STR10##          120-2                            145    "     C.sub.2 H.sub.5                                                                     " "   COOCH(CH.sub.3).sub.2                                                                             92-5                             146    "     "     " "   COOC.sub.4 H.sub.9  oil                              147    "     "     " "   COOCH.sub.2 CF.sub.3                                                                              oil                              148    "     "     " "   COOCH.sub.2CHCH.sub.2                                                                             oil                              149    "     "     " "   CONHCH.sub.3        186-8                            150    "     "     " "   CON(CH.sub.3).sub.2 oil                              151    "     "     " "   CONHC.sub.2 H.sub.5 146-7                            152    "     "     " "   CONHCH(CH.sub.3).sub.2                                                                            146-8                            153    "     "     " "   CONHCH.sub.2CH(CH.sub.3).sub.2                                                                    192-4                            154    "     "     " "   CONH(CH.sub.2).sub.3 OCH.sub.3                                                                    122-4                            155    "     "     " "   CONHCH.sub.2 CH(OC.sub.2 H.sub.5).sub.2                                                           139-40                           156    "     CH.sub.3                                                                            " H   COOK                resin                            157    "     "     " "   COOCH.sub.2 CF.sub.3                                                                              oil                              158    "     "     " "   COOC.sub.4 H.sub.9  oil                              159    "     "     " "    COOCH.sub.2 CH.sub.2 OCH.sub.3                                                                   oil                              160    "     "     " "   CONHCH.sub.3        resin                            161    "     "     " "   CONHCH.sub.2 CH(CH.sub.3).sub.2                                                                   150-9                            162    "     "     " "   CONHCH.sub.2 CH(OCH.sub.3).sub.2                                                                  115-9                            __________________________________________________________________________

BIOLOGICAL EXAMPLES 1. Inhibition of growth in cereals

In dish experiments in a greenhouse, young cereal plants (wheat, barleyand rye) at the 3-leaf stage were sprayed until dripping wet withcompounds according to the invention and with a comparison compound fromDE-A No. 3,217,094 at various active ingredient concentrations (kg/ha).

When the untreated control plants had reached a growth height of about55 cm, the growth in all the plants was measured, and the growthinhibition calculated in % of the control plant growth. In addition, thephytotoxic effect of the compounds was observed. The growth inhibitionwas determined as a percentage value, 100% denoting cessation of growthand 0% denoting growth corresponding to the untreated control plants. Itbecame apparent that the compounds have very good growth-regulatingproperties.

The results are collated in Table 2 below.

                  TABLE 2                                                         ______________________________________                                        Compound Dose     Growth inhibition                                           according to                                                                           (kg of   (%)             Phytotoxic                                  Example No.                                                                            a.i./ha) wheat   barley                                                                              rye   effect                                  ______________________________________                                        39       2.5      27      35    27    no                                               1.25     22      27    25    damage                                           0.62     18      19    18                                            40       2.5      29      35    27    no                                               1.25     23      26    24    damage                                           0.62     18      19    18                                            51       2.5      25      36    18    no                                               1.25     10      31    11    damage                                           0.62      5      23     5                                            54       2.5      21      25    19    no                                               1.25     14      17    16    damage                                           0.62      7      11    10                                            64       2.5      19      37    19    no                                               1.25     16      30    10    damage                                           0.62     11      24     4                                            77       2.5      26      34    27    no                                               1.25     24      29    20    damage                                           0.62     19      23    18                                            81       2.5      28      36    27    no                                               1.25     24      28    24    damage                                           0.62     19      20    19                                            91       2.5      25      32    28    no                                               1.25     17      28    25    damage                                           0.62     11      19    17                                            127      2.5      21      26    19    no                                               1.25     13      19    15    damage                                           0.62      7      12     7                                            130      2.5      22      29    10    no                                               1.25     15      24    14    damage                                           0.62      9      16     8                                            133      2.5      28      35    26    no                                               1.25     22      26    21    damage                                           0.62     18      21    17                                            147      2.5      26      33    21    no                                               1.25     18      24    15    damage                                           0.62     12      11     9                                            ______________________________________                                    

2. Growth inhibition in paddy rice

Rice plants were raised and, at the stage of maximum tillering, treatedwith the compounds according to the invention and with a comparisoncompound from DE-A No. 3,217,094. The substances were applied both byspraying and by direct addition to the water.

The growth in all plants was measured three weeks after treatment, andthe growth inhibition calculated in % of the control plant growth. Inaddition, a possible phytotoxic effect of the compound was looked for.

The results are collated in the table below.

                  TABLE 3                                                         ______________________________________                                        Compound                                                                      according to                                                                             Dose    Growth inhibition                                                                            Phytotoxic                                  Example No.                                                                              (kg/ha) (%)            effect                                      ______________________________________                                        39         2.5     43             no                                                     1.25    41             damage                                                 0.62    33                                                         40         2.5     44             no                                                     1.25    39             damage                                                 0.62    31                                                         51         2.5     30             no                                                     1.25    23             damage                                                 0.62    15                                                         54         2.5     32             no                                                     1.25    25             damage                                                 0.62    17                                                         64         2.5     31             no                                                     1.25    23             damage                                                 0.62    17                                                         77         2.5     40             no                                                     1.25    35             damage                                                 0.62    29                                                         81         2.5     46             no                                                     1.25    41             damage                                                 0.62    35                                                         91         2.5     42             no                                                     1.25    37             damage                                                 0.62    29                                                         127        2.5     31             no                                                     1.25    24             damage                                                 0.62    17                                                         130        2.5     36             no                                                     1.25    25             damage                                                 0.62    19                                                         147        2.5     33             no                                                     1.25    25             damage                                                 0.62    19                                                         ______________________________________                                    

We claim:
 1. A compound of the formula I ##STR11## in which R¹ and R²,independently of one another, are (C₁ -C₄)-alkyl,R³ is halogen, R⁴ ishydrogen, Cl, Br or methyl, X is O, S or N-R⁵, and R⁵ is hydrogen, (C₂-C₆)-alkenyl or (C₁ -C₆)-alkyl, where the alkyl group may be up todisubstituted by (C₁ -C₆)-alkoxy or (C₁ -C₃)-dialkylamino, or up tohexasubstituted by halogen, or an agriculturally suitable saltthereofwith the proviso that R³ is not Cl when R¹ and R² are each CH₃and R⁴ is hydrogen.
 2. A plant-growth regulator, which consistingessentially of an effective amount of a compound of the formula (I) ofclaim 1, or a salt thereof, and a conventional carrier therefore.
 3. Amethod for regulating the growth of plants, wherein an effective amountof a compound of the formula (I) of claim 1, or a salt thereof, isapplied to the plants or the cultivated areas.
 4. A compound as claimedin claim 1, wherein R¹ is C₂ H₅, R² is C₂ H₅, R³ is Cl, R⁴ is H, X is Oand R⁵ is C₂ H₅.